FIGS. 1 and 2 illustrate a prior art lock bar 20, which is located in a warning gate control box, generally designated 21. A box or housing 21 has a cover 27 which may be opened to access internal components. Lock bar 20 is used to lock the gear train 22 of a gate mechanism 23 from moving while a maintainer installs a gate arm 33, such as in FIG. 4, to a conversion bracket or to a gate adaptor 24. Lock bar 20 consists of a steel angle bar that is secured to a pin 25 on a bracket 26 for rotational movement about pin 25. One end 28 of the lock bar 20 can be manually operated to catch in the teeth of a pinion gear 30 of the motor 32 (FIG. 4) to prevent rotation of the gear train 22 and, hence, of the gate arm 33. However, lock bar 20 may be used to restrict gear rotation in only one direction. If a maintainer lifts up on the gate while installing it, the lock bar 20 may become dislodged from the teeth of pinion gear 30, and the gear train 22 will then be free to rotate, including the gate arm 33.
This prior art lock bar 20 requires the maintainer to press a maintenance button located in the gate control box 21 and release it when the gate 33 is in the desired or required position. The end 28 of the lock bar 20 must then be quickly inserted into the teeth of the pinion gear 30 to prevent rotation. The mass of the counterweights 35 located on one end of the gate 33 exerts a force back through the gear train 22 keeping the lock bar 20 wedged in the teeth of the pinion gear 30. Insertion of the lock bar 20 into the teeth of pinion gear 30 is rather tricky because the pinion gear 30 is often in motion. This can present a potential hazard if the lock bar 20 is used incorrectly or if it becomes disengaged.
As can be appreciated from FIG. 1, the lock bar 20 is rotated on the pivot pin 25 until the flat on the end 28 of the lock bar 20 settles in the teeth of pinion gear 30. This “jamming operation” is frequently done with the gear 30 still moving. Any external force applied to the gate arm 33 or to the main shaft 24 (FIG. 4) in the opposite direction will tend to force or push the lock bar 20 out of engagement with the teeth of gear 30. When the maintenance is completed, the lock bar 20 can be removed from pin 25 at the slotted key hole area 29, and repositioned with the enlarged portion of the slotted key hole 29 placed over bolt head 34 such that a slot 31 in end 28 of lock bar 20 rests against pin 25.
A general object of the present invention is to provide an improved lock bar for restricting or limiting movement of a railroad crossing warning gate during maintenance.
Another object of the present invention is to provide a lock bar for restricting or limiting movement of a railroad crossing warning gate in either the up position or in the down position.
A further object of the present invention is to provide a lock bar in the form of a handle with a clutch assembly that permits rotation in one direction, but that restricts or limits rotation in an opposite direction.
Yet another object of the present invention is to provide a lock bar that must be removed when maintenance is completed and before a cover of the gate control box can be closed.